In a camera having a shutter mechanism which is electrically operated, it is desirable to maximize shutter speed while minimizing power requirements for moving the shutter and for holding the shutter in the open and closed positions.
Conventionally, a number of shutter mechanisms have been disclosed. For example, in U.S. Pat No. 3,687,042 by Mizui et al there is described an electromagnetically operated shutter mechanism in which a number of electromagnetic coils are affixed to an actuator frame which is caused to rotate when power is applied to the coils and thereby move a number of shutter blades.
In order to reduce the complexities of these shutter mechanisms, systems have been disclosed in which a permanent magnet is attached to the shutter blade. For example, in U.S. Pat. No. 4,060,313 by Kondo, a thin permanent magnet sheet is sealed in a plastic shutter blade which is driven to the open position by an electromagnetic coil which is fixed about the shutter blade; the blade being biased to the closed position by a spring.
In addition, in U.S. Pat. No. 4,497,557 by Petersen, there is disclosed a shutter mechanism in which permanent magnets of opposing polarities are attached to the opposite ends of each shutter blade to be driven by an electromagnetic coil.
Furthermore, Griffith in U.S. Pat. No. 4,332,450, discloses an electromagnetic actuator which includes a shutter blade having affixed thereto a permanent magnet and which is driven by an electromagnet.
On the other hand, in U.S. Pat. No. 4,514,064 by Kurosu et al, there is disclosed an electromagnetic shutter in which a number of permanent magnets are affixed to a frame, and an electromagnetic coil is attached to the shutter blade which inductively interacts with the permanent magnets to move the shutter blade.
Another electromagnetic actuator for a shutter mechanism, which includes a rotor formed by a pair of offset semicircular portions, is described in U.S. Pat. No. 3,638,550 by Hereford.